MYC as a Biomarker in Aggressive Non-Hodgkin Lymphoma Project Abstract Non-Hodgkin lymphoma (NHL) is the most common hematological malignancy, constituting about 4.6% of human cancers and causing about 3.5% of all cancer deaths in the United States. The incidence of NHL has increased by more than 80% between 1975 and 1991 in the United States - one of the largest increases of any cancer (SEER Cancer Statistics Review 1975-2004). Although there are more than 50 types of NHLs, diffuse large B cell lymphoma (DLBCL) is the most common, accounting for approximately 35 percent of all NHLs. In the United States, DLBCL affects about 7 out of 100,000 people each year. Half of DLBCL patients cannot be cured with the standard rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) therapy. Currently the most common tool for determining DLBLC prognosis is the International Prognostic Index (IPI), which is based on five clinical characteristics (patient age, tumor stage, serum lactate dehydrogenase concentration, performance status, and number of extranodal disease sites). Yet patients with identical IPI scores exhibit marked variability in survival, suggesting the presence of significant residual heterogeneity within each IPI category. Deregulation of MYC, the gene that encodes the c-Myc transcription factor, through translocation, amplification, or other mechanisms is important in the pathogenesis of lymphoid malignancies, including DLBCL. We have assembled an International DLBCL R-CHOP Consortium with 25 medical centers and have established ourselves as a leading team specializing in DLBCL biomarkers. We hypothesize that MYC is a biomarker for DLBCL prognosis and risk-adjusted therapies. In this application, we propose three aims to ascertain the potential of genetic and non-genetic alteration of MYC in DLBCL prognosis and therapy. In Aim 1, we will determine the comprehensive role of MYC in DLBCL prognosis using 3,000 specimens. In Aim 2, we will determine whether DLBCL with MYC translocation differs from those without MYC translocation in gene expression and treatment response. In Aim 3, we will determine the molecular basis of differential prognostic values of MYC CDS and 3'UTR mutations in DLBCL.